The four
Hungry. The least respected of the four and often the most immediately fixable. Low blood sugar makes everything feel more urgent and less survivable. Eat something before you decide anything.
Angry. Including the quiet kinds: resentful, dismissed, stewing over a conversation from three hours ago. Anger narrows the options you can see down to the fastest one.
Lonely. Not the same as being by yourself. You can be lonely in a full room, and a lot of people are loneliest in the specific hour they used to spend a particular way.
Tired. The one people are most likely to push through and least likely to count. Tiredness does not just make a hard moment harder; it makes it harder to remember that you had a plan.
Noticing, not judging
HALT is a check, not a verdict. Discovering that you are three of the four does not mean you have done something wrong; it means you now know why the last hour has felt the way it has, and which lever is nearest.
This matters because the alternative reading, "I should not be finding this so hard", adds a second problem on top of the first one, and the second one is usually heavier.
Where it gets genuinely useful
Once, HALT is a helpful nudge. Kept over time, it turns into something better: if tired shows up before most of your hard moments, that is not a mood any more, it is information. It moves the work earlier, to bedtime or to how a particular Thursday is scheduled, where it is much easier to do.
The same goes for the other three. A pattern of lonely points at a person to contact before the difficult hour rather than during it. A pattern of hungry is sometimes just a missed lunch, three weeks running.
That is the whole argument for writing it down rather than only noticing it: one instance is a mood, a pattern is a plan.
If a moment is bigger than a checklist
In the US, the SAMHSA national helpline (1-800-662-4357) is free, confidential and open every day, and the 988 Suicide and Crisis Lifeline is there in a crisis.